Research Progress of Impurity Removal from Metallurgical Slag and Strengthening Metallurgical Process by External Electric Field

Based on the demand of the development of circular economy, the utilization of metallurgical solid waste has attracted more and more attention, one of the main ways of comprehensive utilization of metallurgical slag is internal recycling in steel plant to replace limestone as smelting flux, so it need to removal of phosphorus and sulfur from molten slag to decrease the burden of dephosphorization and desulfurization in the steelmaking process. In this paper, the current recycling situation of phosphorus-containing steel slag and sulfur-containing waste refining slag is briefly summarized, these relevant researches show that, the methods of dephosphorization of steel slag include reduction method (such as carbon reduction method or silicon reduction method) and gasification method, the dephosphorization ratio with reduction method reached 95.5%, and the greatest dephosphorization rate with gasification method can reach 81.23%, these treatment methods need a long time and treatment temperature is too high. Two main methods to remove sulfur from refining slag, oxidation method and hydrothermal method, oxidative roasting desulfurization and the sulfur removal rate was about 95%. And the latest research progress of using electric field to strengthen slag-metal reaction and component migration in metallurgical melt is also summarized. Electric field treatment of metallurgical melts can affect the physicochemical properties, such as viscosity, solidification structure, grain refinement, material properties, partition coefficient of component and the activity of solute, etc. It can enhances mass transfer reaction in metallurgical process and make oxygen transfer between molten iron and molten copper increase 2~3 times. It also can enhanced the migration ability of components between molten slag and metal, it is a great significance for electric field strengthening slag desulfurization because of enough sulfur ions in slag. There is a non-equilibrium phosphorus capacity different from conventional thermodynamic properties under the action of electric field, the lower non-equilibrium phosphorus capacity improves the phosphorus removal efficiency of phosphorus-containing steel slag.